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<head><meta charset="utf-8"><title>Debugging Obscure Cargo.lock diff · t-cargo · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/246057-t-cargo/index.html">t-cargo</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/246057-t-cargo/topic/Debugging.20Obscure.20Cargo.2Elock.20diff.html">Debugging Obscure Cargo.lock diff</a></h3>

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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/246057-t-cargo/topic/Debugging%20Obscure%20Cargo.lock%20diff/near/242323057" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> XAMPPRocky <a href="https://rust-lang.github.io/zulip_archive/stream/246057-t-cargo/topic/Debugging.20Obscure.20Cargo.2Elock.20diff.html#242323057">(Jun 11 2021 at 09:52)</a>:</h4>
<p>Hello Cargo devs, we're running into a really obscure issue at my work where all of a sudden we're having identical machines generating different <code>Cargo.lock</code> files in CI. We've spent quite a bit of time debugging this issue, and the only concrete link we've found is that different dependencies seem to be disappearing/appearing as a result of the default features for some dependencies changing for some reason between these machines.</p>
<p>We've tested multiple (both older and newer) versions of cargo, new and older versions of the package, and the issue happens regardless. These packages don't use <code>autocfg</code> or anything as far as we can tell that would cause these default features to change without source changes. One of these cases for example is <code>hashbrown</code> having <code>ahash</code> (a default optional dependency) being dropped.</p>
<p>We're currently trying to build a reproducible case to share, but we're having difficulty isolating anything that would point to why this would be happening. Would you's have any insight on how to best debug this kind of issue? I've poured over the <code>CARGO_LOG=trace</code> of the builds and couldn't find anything useful in that.</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/246057-t-cargo/topic/Debugging%20Obscure%20Cargo.lock%20diff/near/242326079" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/246057-t-cargo/topic/Debugging.20Obscure.20Cargo.2Elock.20diff.html#242326079">(Jun 11 2021 at 10:22)</a>:</h4>
<p><span class="user-mention" data-user-id="219696">@XAMPPRocky</span> saw this on twitter yesterday, maybe it's related? (thread) <a href="https://twitter.com/fasterthanlime/status/1402945629811318784">https://twitter.com/fasterthanlime/status/1402945629811318784</a></p>
<div class="inline-preview-twitter"><div class="twitter-tweet"><a href="https://twitter.com/fasterthanlime/status/1402945629811318784"><img class="twitter-avatar" src="https://uploads.zulipusercontent.net/bade379ef25ea9325a0b92fe1f438f895b6b914a/68747470733a2f2f7062732e7477696d672e636f6d2f70726f66696c655f696d616765732f3933363332343335383634393430353434302f6b52524f56336b665f6e6f726d616c2e6a7067"></a><p>say you have a very large workspace

and some crate that's a transitive dependency of many of your direct dependencies, somehow ends up with its "default" feature enabled

say it happens on one machine and not another machine.

what would you do?</p><span>- fasterthanlime 🌌 (@fasterthanlime)</span></div></div>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/246057-t-cargo/topic/Debugging%20Obscure%20Cargo.lock%20diff/near/242326295" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> XAMPPRocky <a href="https://rust-lang.github.io/zulip_archive/stream/246057-t-cargo/topic/Debugging.20Obscure.20Cargo.2Elock.20diff.html#242326295">(Jun 11 2021 at 10:24)</a>:</h4>
<p><span class="user-mention" data-user-id="121055">@Pietro Albini</span> Oh, that’s probably exactly it, because we’re also using cloud smith, and removing it fixed the issue. Thanks for the link!</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/246057-t-cargo/topic/Debugging%20Obscure%20Cargo.lock%20diff/near/242326323" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/246057-t-cargo/topic/Debugging.20Obscure.20Cargo.2Elock.20diff.html#242326323">(Jun 11 2021 at 10:24)</a>:</h4>
<p>no problem!</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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